Write the Expression by Using Rational Exponents Rather Than Radical $7 \sqrt [ 7 ] { x ^ { 3 } }$

Multiple Choice

Write the expression by using rational exponents rather than radical notation. $7 \sqrt [ 7 ] { x ^ { 3 } }$

A) $( 7 x ) ^ { 3 / 7 }$
B) $7 x ^ { 7 / 3 }$
C) $\frac { 7 } { x ^ { 3 / 7 } }$
D) $7 x ^ { 3 / 7 }$